Hello All
My bus has been sitting for a year due to a air dryer leak. So I replaced the air dryer with a new unit and started the bus. The bus didn't build up any air pressure. The gauge shows now air pressure, and the brake pedal is dead. There is no air leaking sound so I don't think it is an air leak. Do you think it is the compressor? Is there something I can check on the compressor such as a valve, etc?
did you disconnect the proper air line connections? disconnect output from air compressor and see if it is producing air. could be the governor if getting air or compressor if not.
The governor inside the air dryer? The air dryer is brand new. I guess that doesn't mean much anymore.
Good suggestion about removing the air line at the compressor and see if it's pumping air.
Quote from: chessie4905 on September 20, 2022, 11:27:18 AM
did you disconnect the proper air line connections? disconnect output from air compressor and see if it is producing air. could be the governor if getting air or compressor if not.
Governor attached to air compressor. 1 1/2 round x about 4"
Oh, ok. Thanks. I will check the governor.
Quote from: chessie4905 on September 20, 2022, 01:06:56 PM
Governor attached to air compressor. 1 1/2 round x about 4"
I'm not sure I remember it all correctly, but I have the impression that there is a communicating air signal line between the air governor and the compressor head actuating valves in the head. This line is how the air governor turns the compressor on and off. There's also another air signal line to the air dryer (AD9?) that actuates the spitter valve on the bottom to purge the collected moisture every time the air governor cycles the compressor. I suspect any number of possibilities of these various communication air signal lines may not be connected as they should be, (or even connected at all). Find and check out tech support online the easily available Bendix Air systems connection diagrams and you should be able to track it down. The Compressor not putting out could be as simple as the actuating, (unloader), valves not being enabled. Not actually a failure of the compressor. I would think any competent mechanic who works on heavy duty air systems would be able to help you troubleshoot and resolve this issue.
I drove out the the shop and started the bus. I couldn't get the line off the back of the compressor because I didn't have a big enough wrench with me. However, I did open the valve on the passenger rear engine hatch just above the rear air tank and it was pumping air. So my guess it has something to do with getting the air to or out of the new air dryer. Is there some sort of valve I need to open on the new air dryer?
Quote from: chessie4905 on September 20, 2022, 11:27:18 AM
did you disconnect the proper air line connections? disconnect output from air compressor and see if it is producing air. could be the governor if getting air or compressor if not.
Signal line to the air drier is missing/corrupt.
The air drier is a giant plug, if it is in the purge mode.
Air compressor governor gets an air preesure signal from a tank via a small line, and a small line goes from the governor to the air drier to coordinate the changes.
Happy coaching!
Buswarrior
The signal wire is a single wire. The air dryer plug had two wires. One was obviously for the signal wire the other was I assumed ground. Neither wire was identified so I made a guess. Could that be the issue?
Quote from: buswarrior on September 20, 2022, 04:57:09 PM
Signal line to the air drier is missing/corrupt.
The air drier is a giant plug, if it is in the purge mode.
Air compressor governor gets an air preesure signal from a tank via a small line, and a small line goes from the governor to the air drier to coordinate the changes.
Happy coaching!
Buswarrior
So if the air compressor governor is bad would I still be able to feel the air from the rear engine compartment air bleed valve. I use that port to connect an separate air compressor in order to fill the bags without running the engine.
Quote from: Jcparmley on September 20, 2022, 05:22:10 PM
The signal wire is a single wire. The air dryer plug had two wires. One was obviously for the signal wire the other was I assumed ground. Neither wire was identified so I made a guess. Could that be the issue?
I'm no expert but get by plenty good. I wouldn't think it a good idea to tap anywhere on the main engine compressor governor with an aux. compressor tap. My preference is the discharge muffler area to tap the aux. electric back up air compressor and even there will effect the governor's normal cycles but the aux. air still has to pass through the drier which is a good aim. Just sharing my thougjts.
wires for air drier should only be for the heater. rest should be tw normal sized airlines and a signal line connecting into correct port on governor. Did the new drier com with a manual for installation? If a Bendix, many places to Google on its operation and trouble shooting.
So we think it might be the governor on the compressor? So please help me understand. If the governor was bad would the valve (in the engine compartment where it says to drain daily) have air? I would think if the governor was not working properly there would be no air in the system at all. Or am I missing something.
Quote from: chessie4905 on September 20, 2022, 06:18:27 PM
wires for air drier should only be for the heater. rest should be tw normal sized airlines and a signal line connecting into correct port on governor. Did the new drier com with a manual for installation? If a Bendix, many places to Google on its operation and trouble shooting.
Do you have the two smaller lines going to the governor mixed up?
all ports on governor are marked. some are plugged.
https://www.sgi.sk.ca/air-brake/-/knowledge_base/air-brake/air-governor
look at ports on air drier. did you get them reversed?
https://www.google.com/search?q=bendix+air+drier+ports&sxsrf=ALiCzsaAUtuiE6bWBfI6iy_CfNUCK1THMg%3A1663752942661&source=hp&ei=7toqY73xJfal5NoPyMaMkAs&oq=bendix+air+drier+ports&gs_lcp=ChFtb2JpbGUtZ3dzLXdpei1ocBADMgcIIRCgARAKOgYIswEQhQQ6CAguELEDEIMBOhEILhCABBCxAxCDARDHARDRAzoOCC4QgAQQxwEQ0QMQ1AI6CwguEIAEEMcBENEDOg4ILhCABBCxAxDHARDRAzoOCC4QsQMQgwEQxwEQ0QM6CwguEIAEELEDENQCOgUIABCABDoICC4QgAQQsQM6CwguEIAEELEDEIMBOgsILhCABBDHARCvAToICC4QgAQQ1AI6CwgAEIAEELEDEIMBOgUILhCABDoICAAQgAQQsQM6BAgAEAo6BAgAEA06BQgAEIYDULcNWNhnYNlsaAFwAHgAgAG5AYgBqxeSAQQwLjIymAEAoAEBsAEB&sclient=mobile-gws-wiz-hp#imgrc=I-kNeW8Ou837UM
Put down the tools and slowly back away...
You've got your pneumatics and your electrics mixed up in your wetware.
If you have good air at the discharge muffler drain "drain daily" then the compressor is cut-in and pumping air.
The signal lines to activate the air compressor governor and the air drier are airlines, smaller lines 1/4 inch give or take.
One line comes from an air tank supply to the governor, the other goes from the governor to the air drier. They have to be in the correct ports.
The purge valve heater on the bottom of the air drier is electric, and should have been designated the native voltage of the bus chassis, 24 volts for us, not the 12 volts that the trucks use. Whether that takes a single wire or a feed and a return, direct attached or a plug, all depends on the model/vintage of the air drier.
Start over, confirming that all connections are correct, plumbing the drier or the check valves backwards will block airflow.
With everything empty, the air drier purge valve should have returned to closed and should be allowing air further into the system. It has a spring, and is triggered open via a pressure signal. So, even if you screw up and don't put the signal line, it will pump, but won't purge.
Every decision you made installing this, must be revisited, and confirmed correct. Find the mistake.
Happy coaching!
Buswarrior
I believe it has to be the governor because the 1/4 signal line is connected correctly to the air dryer. I did not do anything with the governor so all lines are still connected the in the correct port. Would you agree with that assessment?
Quote from: buswarrior on September 21, 2022, 05:28:38 AM
Put down the tools and slowly back away...
You've got your pneumatics and your electrics mixed up in your wetware.
If you have good air at the discharge muffler drain "drain daily" then the compressor is cut-in and pumping air.
The signal lines to activate the air compressor governor and the air drier are airlines, smaller lines 1/4 inch give or take.
One line comes from an air tank supply to the governor, the other goes from the governor to the air drier. They have to be in the correct ports.
The purge valve heater on the bottom of the air drier is electric, and should have been designated the native voltage of the bus chassis, 24 volts for us, not the 12 volts that the trucks use. Whether that takes a single wire or a feed and a return, direct attached or a plug, all depends on the model/vintage of the air drier.
Start over, confirming that all connections are correct, plumbing the drier or the check valves backwards will block airflow.
With everything empty, the air drier purge valve should have returned to closed and should be allowing air further into the system. It has a spring, and is triggered open via a pressure signal. So, even if you screw up and don't put the signal line, it will pump, but won't purge.
Every decision you made installing this, must be revisited, and confirmed correct. Find the mistake.
Happy coaching!
Buswarrior
No, you said you got good air out of the "drain daily" discharge muffler drain?
In which case, the air compressor is pumping, so the governor is in correct configuration.
The way is blocked. Find the blockage that your work has introduced.
It worked before you started.
You touched something, don't make it worse by touching more things, that you didn't touch before.
Happy coaching!
Buswarrior
So I must have plumbed the air dryer wrong?
Jared
Quote from: buswarrior on September 21, 2022, 10:01:14 AM
No, you said you got good air out of the "drain daily" discharge muffler drain?
In which case, the air compressor is pumping, so the governor is in correct configuration.
The way is blocked. Find the blockage that your work has introduced.
It worked before you started.
You touched something, don't make it worse by touching more things, that you didn't touch before.
Happy coaching!
Buswarrior
Was this a straight swap, or a change in air drier models?
If the in and the out are reversed, the air won't go through.
All the reman plastic dirt plugs were removed from all the ports?
The box it came in, all the papers were inspected and read, as to how to prepare it for install?
Not a lot left to check?
Happy coaching!
Buswarrior
It was a swap out. I read the paperwork. I crawled under and took some photos. I believe I have it installed correctly. The supply line comes down from the bus floor and into the supply port on the dryer. The delivery line goes out of the delivery port on the dryer and up and into the two air tanks between the front axles. The 1/4 control like is connected to the control port on the dryer and the heater is wired correctly.
Perhaps I need to remove the supply line and turn the bus on and see if it is blowing air. If it is then something must be wrong with the new dryer or the delivery line to the other tanks is plugged. Does that sound like a logical step?
The first pic is the supply line coming from the floor of the bus.
The second and third pic is the delivery line going to the tanks
Quote from: buswarrior on September 21, 2022, 01:50:01 PM
Was this a straight swap, or a change in air drier models?
If the in and the out are reversed, the air won't go through.
All the reman plastic dirt plugs were removed from all the ports?
The box it came in, all the papers were inspected and read, as to how to prepare it for install?
Not a lot left to check?
Happy coaching!
Buswarrior
Supply and Delivery...
Have you got it connected like the attached diagram?
Loosen off the one you think comes from the compressor and confirm it blows air.
Happy coaching!
Buswarrior
An installation manual for the AD9 attached.
Happy coaching!
Buswarrior
disconnecting the line and checking for air output is the simplest way to diagnose. Sometimes those airlines take a convuluted path, confusing their origin.
I disconnected the supply line and started the engine and it is blowing air. So I know the compressor and the governor is working and I know that the airline is going into the air dryer. I've read the instructions and it doesn't say that something needs to be removed for air to go through the dryer. Am I missing something?
Quote from: chessie4905 on September 22, 2022, 04:01:45 AM
disconnecting the line and checking for air output is the simplest way to diagnose. Sometimes those airlines take a convuluted path, confusing their origin.
Ok. I was wrong. The air is pumping. It is going through the dryer. It is filling the first tank between the axles. However, it is not filling the other tank nor any of the air bags. Air gauge is not reading air build up. Brake pedal still on floor.
All of that is normal, for no air beyond the wet tank.
How much air in the wet tank? A whimper or a hurricane?
At no pressure, a large air leak doesn't make very much noise. Easily overwhelmed by engine noise.
The entire air system staying empty beyond the wet tank, would be a strange thing indeed.
Happy coaching!
Buswarrior
I drained the wet tank and a bunch of water came out. The air is more than a whimper. It was blowing quite hard. Perhaps I should have let it run longer? The other tank next to the wet tank didn't have any air pressure. I looked all the way around the bus and didn't hear any leaks but like you said it could be hard to hear over the engine running. What are my next steps?
Quote from: buswarrior on September 22, 2022, 01:06:40 PM
All of that is normal, for no air beyond the wet tank.
How much air in the wet tank? A whimper or a hurricane?
At no pressure, a large air leak doesn't make very much noise. Easily overwhelmed by engine noise.
The entire air system staying empty beyond the wet tank, would be a strange thing indeed.
Happy coaching!
Buswarrior
consider a standalone compressor and 50 feet of air hose plumbed into coach with a quick connect. sit it where you cant hear it run while you check for leaks. good to have in future, saving running engine to build air and not planning to drive, and for campgrounds to air up before leaving. one like this or similar could be kept in coach for travels. just an example as like tires abnd oil, everyone will state their favorite.
https://www.harborfreight.com/6-gallon-175-psi-high-performance-hand-carry-jobsite-air-compressor-56829.html
I figured it out. It was the brake pedal was rusted down to the floor. The pedal wasn't allowing the air to build up. I broke it loose and now the coach airs up. Now I just have to figure out why the master switch has no power. But that's a different thread. Thank you all for all your suggestions. I greatly appreciate this forum.
The brake pedal being stuck at full travel denying the air to build up is a fascinating mystery. And not right at all.
You better check that air system very closely in various configurations, before going anywhere.
Happy coaching!
Buswarrior
Quote from: Jcparmley on September 22, 2022, 03:36:49 PM
I figured it out. It was the brake pedal was rusted down to the floor. The pedal wasn't allowing the air to build up. I broke it loose and now the coach airs up. Now I just have to figure out why the master switch has no power. But that's a different thread. Thank you all for all your suggestions. I greatly appreciate this forum.
I'm scared!
;D BK ;D
Next question. Where was the air going with the brake pedal on the floor?
Last year when I moved it to it's parking spot on my property one of the rear wheel brakes was locked up. I wasn't able to build enough pressure to release it due to the fact that the valve on the air dryer was stuck open. So in order to move it I bypassed the air dryer by connecting the supply from the compressor to the delivery line to the tanks. This setup was very temporary and leaked air as well. This was just so I could move it a few hundred feet to a new spot out of the way of my snow plowing.
Last week I installed the new air dryer and as you know I was having trouble building air. So I assumed that something was plugged or my air dryer wasn't working. I shared with you all that the air wouldn't build up and the brake pedal was on the floor. I realized yesterday that the brake pedal hinge was rusted and wouldn't allow the pedal to come up. So when I loosened it and raised the pedal up the pressure began to build.
My hope is that I can build up the full pressure to fully release the brakes and move the vehicle to a new spot. However, today I found a new issue. I can start the engine but it stalls after a few minutes. I tried giving it more throttle but it still stalls. Therefore, I haven't been able to run the engine long enough to build up the pressure. This is a mechanical engine. I thought it might be a fuel sense the tank is low and the fuel is over a year old so I disconnected the small inline fuel pump (PO must have installed it to help prime the engine) and I put it in a fresh fuel can. Still stalls after a minute or so. What are your thoughts? I was going to look at the air intake to make sure the filter is not plugged. I also thought about low coolant but am not sure the mechanical engine has a low coolant shutoff. ???
Quote from: buswarrior on September 22, 2022, 05:10:44 PM
The brake pedal being stuck at full travel denying the air to build up is a fascinating mystery. And not right at all.
You better check that air system very closely in various configurations, before going anywhere.
Happy coaching!
Buswarrior
That is a great question. I don't have an answer. I hooked up a small air compressor with a 50 line so I can listen for leaks but didn't hear any. There was a small leak coming from the new air dryer compression fitting but I tightened that down and it sealed. I am curious as well.
Quote from: Lee Bradley on September 23, 2022, 09:29:06 AM
Next question. Where was the air going with the brake pedal on the floor?
I forgot to mention. This valve doesn't move at all and is rusted badly. Could this be part of my air issue?
Valve won't move with link attached or won't move with link disconnected? Latter, bad leveling valve. Looks like coach needed leveling valves anyway.
Check your antifreeze level. On my DL3 if it is low it shuts down after about a minute.
Jim
If you still have no power at the dash, then the engine is being shut down once the air begins to build. Unbolt the air shutdown cylinder on top of the governor and swing it to the side. Just remember once you do that the only way to shut the engine down is by manually pushing the lever on the governor.
The air shutdown cylinder on top of the air compressor governor?
What does that look like? Currently the only way I shut it down is my manually pushing the lever on the governor.
Quote from: thomasinnv on September 24, 2022, 08:42:28 AM
If you still have no power at the dash, then the engine is being shut down once the air begins to build. Unbolt the air shutdown cylinder on top of the governor and swing it to the side. Just remember once you do that the only way to shut the engine down is by manually pushing the lever on the governor.
Oh, the air shutdown on the throttle governor. Got it. How does that system work? Why would it shutdown the engine when the engine is building air? Isn't that what the engine is supposed to do?
Quote from: thomasinnv on September 24, 2022, 08:42:28 AM
If you still have no power at the dash, then the engine is being shut down once the air begins to build. Unbolt the air shutdown cylinder on top of the governor and swing it to the side. Just remember once you do that the only way to shut the engine down is by manually pushing the lever on the governor.
Got it. Thank you for the advice.
Quote from: Jcparmley on September 24, 2022, 01:38:10 PM
Oh, the air shutdown on the throttle governor. Got it. How does that system work? Why would it shutdown the engine when the engine is building air? Isn't that what the engine is supposed to do?
What does this cylinder look like?
Quote from: thomasinnv on September 24, 2022, 08:42:28 AM
If you still have no power at the dash, then the engine is being shut down once the air begins to build. Unbolt the air shutdown cylinder on top of the governor and swing it to the side. Just remember once you do that the only way to shut the engine down is by manually pushing the lever on the governor.
If you are using the rear start without the switch on the dash being on it will shut at around 60 lbs
Wow JC, Sorry you are having multiple headaches. I am NOT a mechanic and ask Buswarrior and BK and others to jerk the reins on my idea if I am sending you down a wrong path. I will take a picture of the air cylinder on my 6V92 in the morning.
Also remember I don't have an MCI but that shouldn't matter. My engine quit running a few times on a trip. (at 65 miles per hour. that was fun). Long story short I had recent service and knew I had clean fuel, fuel filters, oil was new and full, coolant full. All gages normal before shut down(s). And I had been running 5 hours before it hit.
I got two mechanics on the phone and they agreed, so I let them talk me through bypassing the engine run relay. Looked at my schematic, sent them a picture, and on the phone they had me move a wire so it bypassed it and they had me loosen one bolt on the air cylinder so I could swing it to the side to keep from shutting the engine off.
Kind of spooky because as they said it would do once I bypassed that, I had no gages and no jake until I could make it 3 hours away to a guy that replaced that relay. Alllll better. So if you know your panel, that is a maybe, but the guys that correctly diagnosed that said that relay going bad is rare. When I told them I had new everything else, they both said check that with an tester. I did. It was bad. Probably not your problem but it shut me down. Frustrating thing was the relay was dying slowly. Intermittent damn thing. I'd rather something just crap out completely than make me chase 5 other things scratching my head.
Now you should listen to the experts. I'm guessing they will have you check fuel things...
Best of luck
Ted
I just remembered a guy at the bus meet couldn't build air, couldn't find it. Nobody could hear it because it never built air. An old guy (the smart people) told him to push the big yellow air brake button to off. It aired up! It was a bad air brake valve. Probably not it again, but easy to try.
(And I learned it from an old guy, so you gotta try it.)
With water coming out the wet tank and setting for a year you may need a 10 $ set of unloader valves under the head of the compressor and a new head gasket will probably get you up and going in 2 hours. Those tiny valves rust and won't open or close. Check the easy things first like the connections on the skinner valve, It is normally closed with power no air can reach the shutdown till you kill the power and the rod goes out with air on the air cylinder pushing against the shutdown lever on top of the governor that is how the shutdown works. Make sure your rear start switches are in the right position also, those toggle switches on the rear start can be a bitch sometimes. Check the ground wire on the Skinner valve if it breaks or has a lot of corrasion it will shut the engine down,since you have air building now it and it shuts down it almost has to be electrical
Here are the pictures of what I called "the engine shutter offer" until these guys told me what it is called. Hope this helps. If you have one you CAN loosen on bolt and swing it to the side but it is there for low oil, overheat etc so I'd be cautious about disabling it to keep the engine from shutting down so you can air up. It may know something you don't...
There are better was to play with air like a compressor like Buswarrior suggested. Also easier to hear the leak without the 6V92 running.
Best of luck.
What relay is the engine run relay? I replaced the relay below the drivers window that usually clicks and starts the alarm until the bus airs up. However, now that "new" relay doesn't engage. Not sure how to bypass it but I know that I don't have power at the master switch and starter switch.
Quote from: Tedsoldbus on December 08, 2022, 07:24:01 PM
Wow JC, Sorry you are having multiple headaches. I am NOT a mechanic and ask Buswarrior and BK and others to jerk the reins on my idea if I am sending you down a wrong path. I will take a picture of the air cylinder on my 6V92 in the morning.
Also remember I don't have an MCI but that shouldn't matter. My engine quit running a few times on a trip. (at 65 miles per hour. that was fun). Long story short I had recent service and knew I had clean fuel, fuel filters, oil was new and full, coolant full. All gages normal before shut down(s). And I had been running 5 hours before it hit.
I got two mechanics on the phone and they agreed, so I let them talk me through bypassing the engine run relay. Looked at my schematic, sent them a picture, and on the phone they had me move a wire so it bypassed it and they had me loosen one bolt on the air cylinder so I could swing it to the side to keep from shutting the engine off.
Kind of spooky because as they said it would do once I bypassed that, I had no gages and no jake until I could make it 3 hours away to a guy that replaced that relay. Alllll better. So if you know your panel, that is a maybe, but the guys that correctly diagnosed that said that relay going bad is rare. When I told them I had new everything else, they both said check that with an tester. I did. It was bad. Probably not your problem but it shut me down. Frustrating thing was the relay was dying slowly. Intermittent damn thing. I'd rather something just crap out completely than make me chase 5 other things scratching my head.
Now you should listen to the experts. I'm guessing they will have you check fuel things...
Best of luck
Ted
Ok, I started the bus today with no problems. I removed the air line to the air cylinder on top of the governor and put a cap on it temporarily. The bus aired up and did not shut off. So now I know that it was the shut off cylinder that was engaging the shut down lever. I still don't know why.
I was unable to release the parking brakes because my break release button would not stay in the release position. The only way I was able to get the button to stay engaged is when I pressed the brake pedal to the floor. Then the button would stay engaged. However, as soon as I released the brake petal the button would pop and the brakes would be set. Do you think the parking break button has gone bad? Also, why would it pop when I released the brake pedal?
I forgot to mention that I am only building pressure to 95 psi or so even when I use a external air compressor. I don't hear any air leaking when I walk around the bus. I'm wondering why I can't air up to 120 psi?
My parking break button will not stay down until I have 100 PSI on both gages. Might be a Prevost thing, but they don't want you trying to drive without enough air to apply breaks. I don't even try to push it down now until both gages are over 100 psi
If it started probably not the engine run relay, but if it is going bad slowly like mine, it will kick that air cylinder on in a hot minute even if you have good oil pressure and temperature. My bus has a schematic of all the relays on the inside of the door that covers them or I'd have been lost trying to figure out which one to by pass. Sounds like you may have already changed it??
Even with guys in the phone helping me I started off picking the wrong one and new it when the head and tail lights went out. Doesn't sound like you need to do that if it started but if it shuts off again maybe put a meter on that relay. NAPA should have one. The pros had me bypass it by taking the wire going into the left side and putting it with the wire on the right side. But that was a quick fix to get me to a guy with that relay (and it was his last one). Since you are not stranded I would caution against that. It killed all of my gages and the jake which was not a fun way to drive for 3 hours. I worried the whole way. You can get a new relay and change it at your place. If that is not it - be glad you are not trying to change it on I 81 with semi's flying past you and a frightened wife in the bus. That sucked.
I need to shut up and let Buswarrior, BK, Bob Glines and others that know what they are talking about help you but I hope you get it solved.
Good luck JC
Quote from: Jcparmley on December 10, 2022, 12:41:32 PM
I forgot to mention that I am only building pressure to 95 psi or so even when I use a external air compressor. I don't hear any air leaking when I walk around the bus. I'm wondering why I can't air up to 120 psi?
Try setting the pressure on the governor P>S they work opposite of most pressure regulators screw those up after you remove the rubber cover to increase the pressure.You still have an electrical problem to deal with and it will keep shutting down till it is resolved.MCI parking brakes release at 80 lbs the parking valve is not supposed to pop up till the air pressure is in the 20lbs range,where did you hook the supply line for the compressor? you may not be filling all the tanks since that is a dual air brake system and the parking brake valve is not getting a signal from a empty air tank
I hooked the compressor to the inlet in the passenger side rear engine hatch. I attached it where it says "drain daily." Is that not an appropriate place to attach the external compressor?
Here is a pic of the cylinder I removed that was shutting down the engine. As soon as I figure out this electrical issue I will put it back in place.
Quote from: luvrbus on December 10, 2022, 03:13:02 PM
Try setting the pressure on the governor P>S they work opposite of most pressure regulators screw those up after you remove the rubber cover to increase the pressure.You still have an electrical problem to deal with and it will keep shutting down till it is resolved.MCI parking brakes release at 80 lbs the parking valve is not supposed to pop up till the air pressure is in the 20lbs range,where did you hook the supply line for the compressor? you may not be filling all the tanks since that is a dual air brake system and the parking brake valve is not getting a signal from a empty air tank
Mine was bolted on each side. The guys told me to take one bolt out and loosen the other one and just turn it sideways but yours may be different. Keep it connected to air so you see it if pushes the plunger out of the cylinder even though it can no longer shut off the engine. It is at least telling you it wants to shut down. If you bypass the relay, it shouldn't activate the cylinder. When I did the bypass I lost gages and jake as the mechanics told me I would, but the cylinder did not activate all the way to the repair place (3 hours away). Again a bit touchy on doing the bypass. You are effectively hot wiring the bus and bypassing a built in shut down mechanism that is there for reasons we talked about earlier.
If it quits while on bypass I'd say it is up to BW and Luvrbus guys to help you then - but maybe go back to looking at fuel starvation...
I have the same thing you are talking about as far as a place that looks like you can add air. I have not tried it. I think it just fills my aux air tank that sits just below that port. I have not tried it but guess I should. I look at it as one of those "if it is not broken" things for now but I should find out before I need it.
If you run the engine without that cylinder attached, and your relay is working so you have gages, watch your Oil Pressure and Temperature.
FREQUENTLY.
I don't want you seizing your engine because of advice I gave you. I know a bit about that cylinder out of necessity but I am not a DD mechanic....!
(Smart guys: jump in anytime here...).
Someone help me by telling me what a skinner valve is and where do I find it on my bus?
Quote from: luvrbus on December 08, 2022, 08:07:15 PM
With water coming out the wet tank and setting for a year you may need a 10 $ set of unloader valves under the head of the compressor and a new head gasket will probably get you up and going in 2 hours. Those tiny valves rust and won't open or close. Check the easy things first like the connections on the skinner valve, It is normally closed with power no air can reach the shutdown till you kill the power and the rod goes out with air on the air cylinder pushing against the shutdown lever on top of the governor that is how the shutdown works. Make sure your rear start switches are in the right position also, those toggle switches on the rear start can be a bitch sometimes. Check the ground wire on the Skinner valve if it breaks or has a lot of corrasion it will shut the engine down,since you have air building now it and it shuts down it almost has to be electrical
Your C has 2 mounted on the wall in the engine compartment above the engine 1 is for the fast idle the other is for the shutdown both have a 2 wire plug with 1/4 in copper tubing for air supply ,does the fast idle work ? the skinner is doing it's job when the power is off it is shutting the engine down, you get power to rear start and I think your problem is solved inside the rear start there are relays and fuses,the engine safety shut down could be problem also if you have a override button on the dash it flips up to reset the system.
Van bought me the best relay tester for my birthday it so simple plug the relay in push a button and it tells all, no wires to deal with it is a HECS 200-2000 tester
A skinner valve is a term for an air control solenoid operated by electrical power. When power is applied the valve STOPS pressurized air flow from your air system through it, OR when electrical power is applied, ALLOWS air flow through it. I'm guessing " skinner is a brand name or an expression for those valves.
After reading past posts on the subject of the skinner valve, I believe my valve is not getting power. The rear start toggle switch is not getting power. This I believe is the answer to all current problems. I don't have power getting to the start circuit. I have another thread on the same topic so I will be checking that and everyone's help is much needed and very much appreciated. i will jump to that other thread and read through that.
Quote from: luvrbus on December 11, 2022, 04:58:06 PM
Your C has 2 mounted on the wall in the engine compartment above the engine 1 is for the fast idle the other is for the shutdown both have a 2 wire plug with 1/4 in copper tubing for air supply ,does the fast idle work ? the skinner is doing it's job when the power is off it is shutting the engine down, you get power to rear start and I think your problem is solved inside the rear start there are relays and fuses,the engine safety shut down could be problem also if you have a override button on the dash it flips up to reset the system.
Van bought me the best relay tester for my birthday it so simple plug the relay in push a button and it tells all, no wires to deal with it is a HECS 200-2000 tester
Ok, so I still haven't figured out the dash power but I did get a chance to work on the air system. So I found two major air leaks. A fitting broke off the rear tag passenger air bag air hose. The other was in the spare tire compartment. A small air hose broke off and the air fitting as just blowing air. So I caped both of the air leaks and couldn't find anymore. However, the bus still wouldn't build pressure above 75 psi, even with an exterior air compressor hooked up. So could it possibly be the air compressor governor?
Quote from: Jcparmley on December 28, 2022, 06:15:24 PM
Ok, so I still haven't figured out the dash power but I did get a chance to work on the air system. So I found two major air leaks. A fitting broke off the rear tag passenger air bag air hose. The other was in the spare tire compartment. A small air hose broke off and the air fitting as just blowing air. So I caped both of the air leaks and couldn't find anymore. However, the bus still wouldn't build pressure above 75 psi, even with an exterior air compressor hooked up. So could it possibly be the air compressor governor?
No you still have massive leaks somewhere. An external air compressor should be able to fully air up the bus.
Quote from: freds on December 28, 2022, 07:24:38 PM
No you still have massive leaks somewhere. An external air compressor should be able to fully air up the bus.
Ditto. Never mind the whizz bang complicated distractions.
Keep looking, You have leaks.
How are all these lines breaking off? Something wrong here...
Happy coaching!
Buswarrior
Pinch the supply lines off to the DD3 brake chambers and you will probably find your leak
Quote from: luvrbus on December 29, 2022, 06:08:04 AM
Pinch the supply lines off to the DD3 brake chambers and you will probably find your leak
Or, being lazy, i would try to hold the parking control button in the released position while trying to build air. Block the wheels first, of course...
If nothing changes, this does NOT rule out the DD3 as leaking, but is an intermediate diagnostic trick that might save some screwing around. You can't count on the inversion valve to perform correctly under these circumstances, but it is easier than crawling, if it does expose them leaking.
Happy coaching!
Buswarrior
Because the way air tanks are mounted a rusted out air tank with a pin hole is hard to detect too,you may need a larger compressor for more volume to find leaks.I use freon and sniffer sometime, the sniffer will pick up the freon in the general area for a leak then you can pin point it good luck it is not all fun and games finding some leaks. You can take the compressor out of the loop too the unloader valves can stick and circulate the air into the engine crank case and those are impossible to hear.If you have a small compressor, I would rent a larger unit 3 to 5 cubic ft is not much air supply on a brake system on a bus without running the engine compressor (12CFM)
I'm not sure how the line broke off. I heard the air blowing and wiggled my way between the tires and noticed the air bag wasn't filling. So I reached up and felt the air line and sure enough, it was blowing air out of the 90 degree elbow that goes into the top of the airbag on the passenger side tag axle.
Quote from: buswarrior on December 29, 2022, 06:05:01 AM
Ditto. Never mind the whizz bang complicated distractions.
Keep looking, You have leaks.
How are all these lines breaking off? Something wrong here...
Happy coaching!
Buswarrior
Cliffard
What is the best way to pinch the lines?
Quote from: luvrbus on December 29, 2022, 06:08:04 AM
Pinch the supply lines off to the DD3 brake chambers and you will probably find your leak
Quote from: Jcparmley on December 29, 2022, 03:38:45 PM
Cliffard
What is the best way to pinch the lines?
Pinch pliers they look like vise grips only with round bars instead of jaw,Habor Frieght or Amazon
Ok. I hooked up a larger air compressor put a chock under the wheels, and held in the break release button and the bus still wouldn't air up past 75 psi. The drive axle bags have air. The tag bags do not. The only air I hear is the air going into the air dryer. During the spring I replaced the air dryer and I checked the instructions and know I have it installed correctly. I know the tanks are getting air because I can release air when I pull the valve on the bottom of each tank. The engine is not on so I know it's not the compressor. What are your thoughts?
Is the compressor far enough away so you can listen for air leaks?
Quote from: Jcparmley on January 02, 2023, 09:32:06 AM
Ok. I hooked up a larger air compressor put a chock under the wheels, and held in the break release button and the bus still wouldn't air up past 75 psi. The drive axle bags have air. The tag bags do not. The only air I hear is the air going into the air dryer. During the spring I replaced the air dryer and I checked the instructions and know I have it installed correctly. I know the tanks are getting air because I can release air when I pull the valve on the bottom of each tank. The engine is not on so I know it's not the compressor. What are your thoughts?
On the C between the manual 2 dump valves for the tag there is a plug you can remove and try to air up the tag,there is also a electric dump valve in that plumbing to dump the air from the driver's seat,that valve maybe stuck or turn on dumping the air, it is all on the passenger's side at the engine compartment you can see the wiring and plug going to the electric valve and the 2 manual valves be sure they are closed
good luck
My air compressor is a 100 feet away and I can hardly hear it when it's running. This afternoon I removed the air compressor discharge hose and hooked my external air compressor to the discharge line heading straight into the air dryer. I figured this would tell me if my engine air compressor was the problem. It still wouldn't air up beyond 75 psi. I did hear air filling the air dryer. So I decided to jack the bus up and block it. I then crawled under and found a major leak in the hard line going from the air dryer to the wet tank.
The copper line had a hole in it. I cut the copper line above the hole and got a new copper compression sleeve. However, I can't find the correct fitting to go from the copper line to the air dryer. So I thought I would just remove the copper line and make a new line to go from the air dryer to the wet tank. Tomorrow I will remove the copper line from the wet tank and have a diesel shop make me a DOT approved line to go from the air dryer to the wet tank. However, I can't seem to find in my manual what size fitting I need for the wet tank. Do any of you know what type of threaded fitting goes into the wet tank? I am assuming its NPT. The DOT Nylon Line and fitting is compression, so I will need compression to NPT.
Take all the wreckage with you to the hose shop, lay it on the counter, and they'll fix you up.
Nothing we tell you is more accurate than what you unwind out of the fittings.
Happy coaching!
Buswarrior
Most air tanks have the Bendix thread not NPT yours could be NPT you never know who has been there before you, all buses used the Bendix fittings (B/W ) on the air system from the factory some are the same size as NPT and some are not
What is a Bendix thread and where can I get the fitting?
Quote from: luvrbus on January 02, 2023, 05:51:53 PM
Most air tanks have the Bendix thread not NPT yours could be NPT you never know who has been there before you, all buses used the Bendix fittings (B/W ) on the air system from the factory some are the same size as NPT and some are not
Quote from: Jcparmley on January 02, 2023, 06:53:15 PM
What is a Bendix thread and where can I get the fitting?
Hose supply outlets sells the Bendix if you need it ,the Bendix fitting will have a long nut for a flare fitting to prevent breaking of the copper lines auto parts and hardware stores sells cheap made fitting that break in time air brake fitting will have the DOT stamp and you can see the difference,they cost more too
Some store fittings don't thread on. Different. Btdt. Good, correct ones are stamped bw or dot. Thicker material. McMaster Carr also carries correct supplies and fast shipping, if not available locally.
So do I look for a flare fitting or a compression?
Quote from: luvrbus on January 03, 2023, 03:46:34 AM
Hose supply outlets sells the Bendix if you need it ,the Bendix fitting will have a long nut for a flare fitting to prevent breaking of the copper lines auto parts and hardware stores sells cheap made fitting that break in time air brake fitting will have the DOT stamp and you can see the difference,they cost more too
Quote from: Jcparmley on January 03, 2023, 07:45:50 AM
So do I look for a flare fitting or a compression?
Dot compression fitting work they are different than the ACE hardware compression fittings
I need to find 3/4 Female DOT/Bendix Thread to 1/2 Female NPT Thread.
I have the fitting for the copper air pipe. It's 3/4 DOT/Bendix. I also found the male fitting that it mates with to compress the sleeve. I have included those pics in this post.
What I need now is a fitting to go from the 3/4 male DOT to the Male 1/2 NPT on the Nylon Hose that was made by the diesel shop.
What is the thread "code" for Bendix thread? Is it DOT or something else?
They may be a tough find,on the air system any transition was made in one fitting or on the hose end
Try a hydraulics shop. Good chance they might be able to help you out.
Many fittings use a standardized thread in an inch or metric size measured as an inch fraction (or mm count) and a thread pitch such as 3/4-16 which is a fine pitch thread that would be used in fittings. You can easily measure the diameter and pitch with calipers. A 16 pitch would be 4 threads in 1/4". If your fitting uses a standard fine thread finding a match should be no problem.
Jim
So I fixed the leak at the air dryer. Now I am able to build enough air pressure for the brake release button to stay down. However, the breaks still won't release. I tried holding the brake pedal to the floor for 30 seconds to a minute. I tried putting it in reverse and forward. I tried pumping the brake. I can't get it to release. Any suggestions?
Waiting for BW to correct me but it seems like you are not supposed to apply the parking brake when you have the regular brake pedal pushed down. Something about making it hard to release the parking brake? So if that might be your problem maybe it just takes some energetic bouncing on the brake pedal while simultaneously trying to release the parking brake? Hopefully? Just a thought.
Jim
What is "enough pressure"?
It is either filling up, and the air drier purges, or it isn't.
How long has it been parked since it last moved?
How old is the inversion valve?
Concurrent application of service and parking.... something is ringing my "mythology" bell, I need to refresh my memory...
happy coaching!
buswarrior
Takes at least 85psi to release the DD3 brake lol 120 psi is better,the DD3 chambers need to vent the air to release can you hear escaping air ? if so then the shoes are stuck on the drum
Need a full pedal application of 120psi, especially after sitting a while. Once you have 120, push brake pedal fully to floor, THEN push or pull button to release brakes.. ( some buttons need pushed to release, some need pulled. Whichever)Until you can get the pressure to that , don't bother. Try running engine now AND external air supply.
I do not have 120 psi. What I meant is I have enough pressure that break release button stays down and doesn't pop back up. I thought the parking brake only needed 85 psi. It has been sitting for over a year in it's current spot. I don't know how old the valve is. I never changed it. I will keep chasing down more air leaks until I can get 120 psi or the air dryer purges. I was hoping to release the brakes and move it closer to my shop so I can track down more leaks. Right now its a couple hundred yards from my shop. I wouldn't be surprised if the brake's are rusted to the drums. Any clever way to break them free?
Quote from: buswarrior on January 04, 2023, 12:19:03 PM
What is "enough pressure"?
It is either filling up, and the air drier purges, or it isn't.
How long has it been parked since it last moved?
How old is the inversion valve?
Concurrent application of service and parking.... something is ringing my "mythology" bell, I need to refresh my memory...
happy coaching!
buswarrior
You mean when I press the brake pedal? Yes, I hear air escaping. I bet the shoes are stuck on the drum.
Quote from: luvrbus on January 04, 2023, 01:18:08 PM
Takes at least 85psi to release the DD3 brake lol 120 psi is better,the DD3 chambers need to vent the air to release can you hear escaping air ? if so then the shoes are stuck on the drum
Again, never mind the distractions.
Find and stop the leaks.
It isn't moving without proper air pressure.
Full stop.
happy coaching!
buswarrior
Here is a lengthy post from a few years back. Slow reading to comprehend, but should help. Also download the Bendix air brake manual pdf. Available in several locations on the net. FREE!
https://www.busconversionmagazine.com/forum/index.php?topic=31316.15
Quote from: Jcparmley on January 04, 2023, 02:39:11 PM
You mean when I press the brake pedal? Yes, I hear air escaping. I bet the shoes are stuck on the drum.
No when you push the PBV in you should here air coming from the DD3 chambers if you have air pressure leaking when you push the pedal down means you have leaks,pushing the pedal down with the right psi releases the rachet locks on the DD3 brakes when let the pedal up then you hear air.The inversion valve BW keeps talking about on DD3 brakes controls the rachet locks on the DD3 that is the valve only purpose those are easy to check or clean look on the Bendix site and there you can see the valve to help you identify it,The rachet balls will rust and old grease build up will cause those not to release, the chambers have grease fitting try pumping new grease when you get the right PSI.? did the bus have that many leaks when it was parked
Quote from: Jcparmley on January 04, 2023, 02:37:48 PM
I do not have 120 psi. What I meant is I have enough pressure that break release button stays down and doesn't pop back up. I thought the parking brake only needed 85 psi. It has been sitting for over a year in it's current spot. I don't know how old the valve is. I never changed it. I will keep chasing down more air leaks until I can get 120 psi or the air dryer purges. I was hoping to release the brakes and move it closer to my shop so I can track down more leaks. Right now its a couple hundred yards from my shop. I wouldn't be surprised if the brake's are rusted to the drums. Any clever way to break them free?
Any clever way to break them free? First chock your tires make sure the slack adjuster can be pulled back (may need a flat screw driver or prybar) this means your brakes are released take a big hammer pound on the edge or outer part of the drum if that don't do it tap on the metal part of the brake shoe . The drum will ring if they are released and solid sound if they are not. Remember you have upper and lower shoes both maybe stuck. If you can't reach the drum with a hammer find a solid steel shaft the right lenth also a good air hammer may work.
If your parking brakes won't release and you want move the bus into the shop like you said you can back the slack adjusters off can be a little tuff to do but can be done if they are manual slack push the keeper in may have to tap it in use a 9/16" 6 point socket and longer ratchet normally counterclockwise to back it off you have to pull hard at first. auto slacks same thing only many different designs you'll have to look it up. Remember you won't have parking or service brakes on that axle make sure your other brakes are setup before you move it and may have to break the shoes free after you back off the slacks. Good Luck!
When I press the brake pedal I only hear air when I lift it up. I did not notice many leaks when I parked the bus. To get to the grease fitting do I need to jack the bus up and block it?
Quote from: luvrbus on January 04, 2023, 03:57:42 PM
No when you push the PBV in you should here air coming from the DD3 chambers if you have air pressure leaking when you push the pedal down means you have leaks,pushing the pedal down with the right psi releases the rachet locks on the DD3 brakes when let the pedal up then you hear air.The inversion valve BW keeps talking about on DD3 brakes controls the rachet locks on the DD3 that is the valve only purpose those are easy to check or clean look on the Bendix site and there you can see the valve to help you identify it,The rachet balls will rust and old grease build up will cause those not to release, the chambers have grease fitting try pumping new grease when you get the right PSI.? did the bus have that many leaks when it was parked
what part of the country are you??? Maybe someone hands on can help.. Looks like your learning system under fire--you won't forget it! Spray bottle with dishwasher soap and water is your friend. squirt and look for bubbles. You have the best trying to help so be patient...my last mci 1978 had air beams rusted out.. used block off plates to solve problem. I am not famiular with the 102c3..
The bus is dual air system watching the gauge should narrow his search when checking for a leak where the leak is on the rear or front of the bus,If he has field mice those love the taste of the DOT plastic lines and wiring for dessert
yep on mice.. had one chew airline in tunnel. someone had bright idea to use soy oil in process. didn't last long.
I live in just west of Madison Wisconsin. My bus only has one air gauge and only one needle in the gauge, so I can't tell what the pressure is in the rear and front separately. We do have field mice.
Quote from: luvrbus on January 05, 2023, 10:46:29 AM
The bus is dual air system watching the gauge should narrow his search when checking for a leak where the leak is on the rear or front of the bus,If he has field mice those love the taste of the DOT plastic lines and wiring for dessert
When you are airing the bus up does it reach about 60psi at a steady pace then slows down ?
JC :went to college in madison and met first wife there. About 400 miles south of you now. We have members in that area.. Hopefully one of them can lay hands on. Made that 402mile trip a bunch of times. Check your aux air tank in steering compartment. the bottom of those seem to rust out and are hard to detect. Some will cringe at this suggestion. Or throw things at their computer. Try introducing Air tool oil into where you are providing aux air. It is hell on air dryers but at this point it might just free up a stuck valve. Knowing where you are helps understand possible ice in lines etc. Has any thing improved with this brief warm up? BW and LV bus understand cold and have massive experience with air systems..In bus & equipment..Will continue to monitor progress..Bob
Found an air leak in the fold out step actuator so I removed that line and capped it. Tomorrow after church I will go around with my spray bottle and try to find more. The only air I hear is the air dryer filling up, but when I go under and feel around all the fittings I don't feel any air escaping so I am assuming the sound is normal. I must have more leaks somewhere because I can't get it to build up to 120 psi or where the air dryer purges.
Quote from: Jcparmley on January 07, 2023, 01:49:42 PM
Found an air leak in the fold out step actuator so I removed that line and capped it. Tomorrow after church I will go around with my spray bottle and try to find more. The only air I hear is the air dryer filling up, but when I go under and feel around all the fittings I don't feel any air escaping so I am assuming the sound is normal. I must have more leaks somewhere because I can't get it to build up to 120 psi or where the air dryer purges.
I wouldn't count on finding almost any leak by trying to feel sir with dry hands. It would have to be a massive leak to feel.it that way. On the other end of the scale a slow leak could take many minutes to show up under soapy solution. Just saying.
Make sure you spray soapy water on any aeroquip hoses the hose itself especially the old hard ones air will bleed through without you hearing or feeling it. Had a air leak I could find for over a year when I hit the air line with soapy water the whole line foamed up (hose).
Quote from: Jcparmley on January 07, 2023, 01:49:42 PM
Found an air leak in the fold out step actuator so I removed that line and capped it. Tomorrow after church I will go around with my spray bottle and try to find more. The only air I hear is the air dryer filling up, but when I go under and feel around all the fittings I don't feel any air escaping so I am assuming the sound is normal. I must have more leaks somewhere because I can't get it to build up to 120 psi or where the air dryer purges.
If you have air wipers check the dash area the wiper controls can leak enough to prevent air up
Ok, I didn't think of that. I will check tomorrow.
Quote from: luvrbus on January 07, 2023, 03:48:24 PM
If you have air wipers check the dash area the wiper controls can leak enough to prevent air up
Ok, I spent my whole day off today looking for air leaks. I believe I got them all. I am now able to build pressure to over 120 psi. However, my air dryer did not purge. I kept waiting but nothing happened. I tried to release the breaks but didn't have any success. They must be rusted to the drum. I tried shifting back and forth to try to release them but didn't have any luck.
Quote from: Jcparmley on January 09, 2023, 04:07:35 PM
Ok, I spent my whole day off today looking for air leaks. I believe I got them all. I am now able to build pressure to over 120 psi. However, my air dryer did not purge. I kept waiting but nothing happened. I tried to release the breaks but didn't have any success. They must be rusted to the drum. I tried shifting back and forth to try to release them but didn't have any luck.
First chock your tires make sure the slack adjuster can be pulled back (may need a flat screw driver or prybar) this means your brakes are released take a big hammer pound on the edge or outer part of the drum if that don't do it tap on the metal part of the brake shoe . The drum will ring if they are released and solid sound if they are not. Remember you have upper and lower shoes both maybe stuck. If you can't reach the drum with a hammer find a solid steel shaft the right lenth also a good air hammer may work.
If your parking brakes won't release and you want move the bus into the shop like you said you can back the slack adjusters off can be a little tuff to do but can be done if they are manual slack push the keeper in may have to tap it in use a 9/16" 6 point socket and longer ratchet normally counterclockwise to back it off you have to pull hard at first. auto slacks same thing only many different designs you'll have to look it up. Remember you won't have parking or service brakes on that axle make sure your other brakes are setup before you move it and may have to break the shoes free after you back off the slacks. Good Luck!
Quote from: Jcparmley on January 09, 2023, 04:07:35 PM
Ok, I spent my whole day off today looking for air leaks. I believe I got them all. I am now able to build pressure to over 120 psi. However, my air dryer did not purge. I kept waiting but nothing happened. I tried to release the breaks but didn't have any success. They must be rusted to the drum. I tried shifting back and forth to try to release them but didn't have any luck.
The governor controls the purge cycle on the drier it could need adjusting you may not be reaching the psi the governor is set for or the drier is not getting the signal from the governor
Confirm pressure in the parking tank, or you are wasting your time bashing on things.It is blind to the dash air gauge.
With all the trouble you have had, absolutely no assumption of proper function can be made.
A tire gauge fits neatly onto a male air hose fitting...
Happy coaching!
Buswarrior
Is the parking tank is under the bus by the front axle on the passenger side, correct? I can crawl under there and put a gauge on the tank where the moisture release valve is. Otherwise, I have a male hose fitting in the rear passenger engine hatch where I hook up my external air compressor. I could check it there as well.
Quote from: buswarrior on January 10, 2023, 11:16:35 AM
Confirm pressure in the parking tank, or you are wasting your time bashing on things.It is blind to the dash air gauge.
With all the trouble you have had, absolutely no assumption of proper function can be made.
A tire gauge fits neatly onto a male air hose fitting...
Happy coaching!
Buswarrior
Take the pressure at the tank, taking it back there doesn't cornfirm what you need to know, the real pressure in that tank.
First clue is presence of healthy air when you open the drain on the parking tank. A male airline fitting may screw into what you have there, if you"re lucky.
Using what strategies, how many times, did you attempt to release the parking brake? Did you wait for the air to recover between attempts? With the bus in your condition, there's a half hour of stomp, release, forward, backward, leaning on it with the drive train, air build up, stomp, etc, before ever thinking about leaving the driver's seat.
The lack of air drier blow off is also still a highly susicious issue, pointing to continued air system integrity problems. Changing parts willy nilly just introduces more self inflicted malfunctions.
Does the air pressure distinctly stop climbing at EXACTLY the same place on the gauge, every time it builds back up?
Put down the tools, stow the keyboard, and get back in the driver's seat...
Happy coaching!
Buswarrior
I spent well over an hour doing the exact procedure you recommend. I always let the air build up before releasing the brake, doing a hard stomp and putting in forward and reverse. My gauge always stops at the same spot every time. I have drained all the tanks multiple times. I spent the entire day using soapy water to find all the leaks. I sprayed down every tank and air fitting I can find, including taking the windshield wiper control unit out and inspecting for leaks. I have followed all the instructions that I have been given. Everyday I work at it some more and am very thankful for all the advice. I
I will hook up a pressure gauge to the Brake Tank and see what the pressure is and let you all know. Thanks for all the help everyone, I really appreciate it.
Quote from: buswarrior on January 10, 2023, 07:23:24 PM
Take the pressure at the tank, taking it back there doesn't cornfirm what you need to know, the real pressure in that tank.
First clue is presence of healthy air when you open the drain on the parking tank. A male airline fitting may screw into what you have there, if you"re lucky.
Using what strategies, how many times, did you attempt to release the parking brake? Did you wait for the air to recover between attempts? With the bus in your condition, there's a half hour of stomp, release, forward, backward, leaning on it with the drive train, air build up, stomp, etc, before ever thinking about leaving the driver's seat.
The lack of air drier blow off is also still a highly susicious issue, pointing to continued air system integrity problems. Changing parts willy nilly just introduces more self inflicted malfunctions.
Does the air pressure distinctly stop climbing at EXACTLY the same place on the gauge, every time it builds back up?
Put down the tools, stow the keyboard, and get back in the driver's seat...
Happy coaching!
Buswarrior
If you have help with someone pushing the brake pedal down and if you can get under the bus to see the DD3 brake chambers if you notice any movement pushing the pedal, then you have air pressure or remove the supply line and you can hear it, the locking port supply is on the front where it mounts to bracket ,A DD3 brake will release without pushing the pedal if the air pressure is good and locks are not frozen from rust, it just takes longer,you are told to use the same process with spring brakes which I never do BTW
I asked my diesel mechanic to come to and do what you suggested. He said he can hear the air in the chamber but the tensioner and the shaft was not moving. He thought either there is a problem in the chamber or the brake shoes are rusted to the drum. We had a lot of rain and the ground is to soft to jack up the bus right now. In a few days it will freeze again and we will jack the bus up, get under and hammer the drum to see if it will release. If that doesn't work then I will probably need to look at the chambers themselves.
Quote from: luvrbus on January 11, 2023, 06:47:46 AM
If you have help with someone pushing the brake pedal down and if you can get under the bus to see the DD3 brake chambers if you notice any movement pushing the pedal, then you have air pressure or remove the supply line and you can hear it, the locking port supply is on the front where it mounts to bracket ,A DD3 brake will release without pushing the pedal if the air pressure is good and locks are not frozen from rust, it just takes longer,you are told to use the same process with spring brakes which I never do BTW
When it dries up slide under and pump new grease into the lock there is a grease zert on the bottom of each chamber pump the old grease out, the fitting is hard see but it is there
I will grease the chamber and let you know how it goes.
Don't go crazy with grease.
I'm still struggling to get this bus to release its breaks. It has been very cold and I haven't been able to get out there. I did get the rear of the bus jacked up so the mechanic could get under and see if the canisters are releasing the brakes, however, to my bad luck, when the mechanic came out the bus wouldn't air up past 50 psi again. Three weeks ago I had it airing up just fine over 100 psi, but the brakes wouldn't release. Now it won't air up past 50 psi. I don't hear any leaks and three weeks ago I chased down a the leaks with the soapy water bottle. Interesting thing about today is the accessory tank didn't have any air in it. So I am thinking their is a valve sticking or frozen. Which valve do you think it might be?
What's cold?
Daytime highs, nighttime lows?
How did you make the other leaks stop?
An empty accessory may be a preesure protection valve, but more likely just means more big leaks, and it doesn't get high enough to make much noise.
Until you have replaced everything pneumatic that is beyond its service life, this is what happens, you leave it, and there's more trouble. There is nothing static about an old bus.
And, in relative terms, they leak worse in the "cold" due to shrinkage.
Happy coaching!
Buswarrior
Last few weeks the temp has been in the teens with a few nights around zero. Today was nice and warm at 36 degrees. Tomorrow is going to be raining and 39 degrees. I am just trying to get this bus moved and onto the pavement closer to my shop. I am trying to get it going because I have a person who wants to purchase it. My plan has been to get it moved closer to the shop on pavement so I can block it better and get under it and take a good look at things. I need to drive it .25 miles to the diesel mechanic and have them do a proper check of the air and brake systems before I sell it.
I have been diagnosed with a spine disease and just can't do the hard work anymore. I had good air pressure a few weeks ago when I sprayed everything down with soapy water and fixed a bunch of small leaks. Now I am back to not building air pressure. Tomorrow I am going to crawl under and check the pressure at the parking tank.
Is there a way to introduce alcohol into the air system after the air dryer to "thaw" the system if I do have a frozen valve?
Quote from: buswarrior on February 26, 2023, 04:12:09 PM
What's cold?
Daytime highs, nighttime lows?
How did you make the other leaks stop?
An empty accessory may be a preesure protection valve, but more likely just means more big leaks, and it doesn't get high enough to make much noise.
Until you have replaced everything pneumatic that is beyond its service life, this is what happens, you leave it, and there's more trouble. There is nothing static about an old bus.
And, in relative terms, they leak worse in the "cold" due to shrinkage.
Happy coaching!
Buswarrior
Until the temperature is steadily over 40 degrees, you are wasting your time. Frozen needs more than a few hours to thaw out. We see this problem for years here on many coaches in freezing temperatures.
Alcohol won't thaw a frozen system it prevents a system from freezing when mixed with the moisture and air.Wait till in warms for a few days or skirt the bottom with tarps and use a shop heater is the only choice you have
Quote from: chessie4905 on February 26, 2023, 05:54:15 PM
Until the temperature is steadily over 40 degrees, you are wasting your time. Frozen needs more than a few hours to thaw out. We see this problem for years here on many coaches in freezing temperatures.
hey, so busnuts have to plan to hibernate like a bear when the temps fall under 40? lol
No,,, but a heated garage wouldn't hurt..>>>Dan
Quote from: windtrader on February 27, 2023, 10:28:48 AM
hey, so busnuts have to plan to hibernate like a bear when the temps fall under 40? lol
Redundant heat helps too. We once guessed it right when we held a burnzomatic torch on an air check valve and away we went from being froze down. Dryer helps too, has happened since installing one.
The purge valve on his drier is probably frozen.The heater on the driers come on at 35 degrees but if the batteries are disconnected they don't do much without power
Quote from: dtcerrato on February 27, 2023, 11:04:57 AM
Redundant heat helps too. We once guessed it right when we held a burnzomatic torch on an air check valve and away we went from being froze down. Dryer helps too, has happened since installing one.
I carry a propane torch with extra bottle,lol I use the food torch head on mine something that will put out the heat you can buy those on Amazon for 20 to 40 bucks I have the Koacki 2500 degrees will get the job done in a hurry.I use mine mostly to start campfires and grills with but have it just in case of a freeze up in the air system
That's a good idea. Thanks
Quote from: luvrbus on February 26, 2023, 07:48:04 PM
Alcohol won't thaw a frozen system it prevents a system from freezing when mixed with the moisture and air.Wait till in warms for a few days or skirt the bottom with tarps and use a shop heater is the only choice you have
Yes, the batteries are disconnected when I am not at the bus. I can use a heat gun and warm the bottom of the dryer.
Quote from: luvrbus on February 27, 2023, 11:18:14 AM
The purge valve on his drier is probably frozen.The heater on the driers come on at 35 degrees but if the batteries are disconnected they don't do much without power
Good current serviced air drier, air tanks drained frequently, until not seeing moisture due to effective drier operation, eliminates a lot of issues. Short 20 minute diagnostic runs may crete more moisture than drier can remove on that short cycle. Below 35° with an inop drier exhaust port heater can cause similar issues. Very important to verify operation in cold Temps. You should hear a sharp exhaust sound at that port if operating.
A bad air compressor pumping excessive oil into air system can render desiccant ineffective. Also, about every 6 months to a year, air tank drains should be left open for 12 to 24 hour period to allow all oil and sludge to drain. Collect the residue to inspect what comes oil. Lots of grey/ tan cream composition, (water/oil mix) is a good sign of excessive compressor wear.
Course, you're planning on unloading this coach asap, but info should be helpful regardless.
As noted, just wait for the temps to stay above freezing, waste of time and effort to screw with this until freezing can be ruled out.
For future readers, air system maintenance is a 24/7/365 job.
Air drier maintained, fresh desiccant and purge valve heater tested, drains purged regularly, and a busnut will enjoy trouble free cold weather operation.
The rule is that the previous owner did NOT keep it up, and we inherit a cold weather problem.
Don't bet against yourself, the exceptions become the rule...
happy coaching!
buswarrior
personal note: I have a foot of steel in my back since 2012.. have completed another bus conversion since then. took longer but you learn to work smarter.. Might take a minute to let things thaw out and get use to being limited physically .. Best of luck on both. Bob